Ionic Liquid Binary Mixtures, Zeolites, and Ultrasound Irradiation: A Combination to Promote Carbohydrate Conversion into 5-Hydroxymethylfurfural

The efficient conversion of biomass into value-added compounds under mild and safer conditions is a cornerstone of present research efforts to meet the needs of the chemical industry with sustainable development. In this work, we studied the dehydration of fructose, glucose, and sucrose into 5-hydroxymethylfurfural (5-HMF), catalyzed by HY zeolite, in three ionic liquid mixtures differing for the cation, aromatic, or aliphatic. We investigated the effect of several operational parameters such as temperature, catalyst loading, zeolite counterion, solvent mixture, and added chloride. In the optimal experimental conditions, we obtained good conversions to 5-HMF especially for fructose and sucrose, 73% and 62%, using the relatively low temperatures of 80 and 120 °C, respectively. Interestingly, in the used experimental conditions, the solvent-catalyst systems can be reused for at least 6 cycles without loss in performance. We also investigated the dehydration of fructose under sonochemical activation, obtaining a conversion to 5-HMF of 71% in 0.5 h, at the remarkably low temperature of 40 °C.